Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
  • H02H7/28—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for meshed systems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/08—Locating faults in cables, transmission lines, or networks
  • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
  • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
  • H02J1/14—Balancing the load in a network
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
  • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
  • G01R19/14—Indicating direction of current; Indicating polarity of voltage
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
  • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
  • G01R19/2513—Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
  • G01R31/52—Testing for short-circuits, leakage current or ground faults
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Definitions

• System comprising a power flow control device used to control the distribution of currents in a mesh network and means of protection of said device
• the present invention relates to a system which comprises a power flow control device used to control the distribution of currents in a mesh network and suitable protection means making it possible to protect said device in the event of an electrical fault.
• a network is a set of overhead lines or cables hereinafter called “links” which connect devices (or terminals) to each other so that they exchange energy.
• links which connect devices (or terminals) to each other so that they exchange energy.
• the devices which supply or consume energy are generally electronic power converters called “converter stations”.
• the current has several possible paths to go from one converter station to another.
• the currents in the connections are distributed according to the characteristics of the connections (in continuous, this characteristic is the resistance of the connection).
• Figure 1 shows a mesh network with a single mesh.
• This network thus comprises three nodes which are each at a determined voltage and three links, called first link connecting the first node to the second node, second link connecting the first node to the third node and third link connecting the second node to the third node.
• the three voltages V a , V b , V c represent the voltages imposed by conversion stations.
• the three resistors R1, R2, R3 represent the resistances of the links.
• Each converter station is able to inject or extract power from the network.
• the currents (h, l 2 , L) in each link are not controlled by the converter stations. Indeed, each converter station imposes on the network, at the node where it is connected, a determined voltage. While the current in each converter station is lower than its maximum current, it is possible to reach operating points for which a link is crossed by a current higher than its maximum current while other links in the network (which could be used to transfer energy) are under load.
• the current has two possible paths to go from station B to station A:
• the distribution between the two paths will be determined in particular according to the values of the resistance of the links and the voltages imposed by the network conversion stations.
• Some of these devices use a single voltage source connected in series with a link, as shown diagrammatically in FIG. 2. The adjustment of this voltage makes it possible to modify the distribution of currents in the network. Architectures of this type have been described in patent applications WO2010 / 115452A1, WO2013 / 013858A1.
• FIG. 3 Another power flow control device described in patent application WO2013 / 178807A1 (or its correspondent US2015 / 180231 A1) and shown diagrammatically in FIG. 3 consists of inserting two voltage sources (V xi , V x2 ) in series each with a separate link and a voltage source (V x0 ) in series with a converter station.
• V xi voltage sources
• V x0 voltage source
• Patent application EP3032677A1 also describes a system used in a mesh network, comprising a power flow control device.
• the faults can be said to be internal and relate to the failure of one or more of the components of the device itself (inductance, capacitor, switch, pole-to-earth fault at the frame of the device ...) and so-called external, that is to say from the DC network itself, such as a pole-to-earth or pole-to-pole type fault.
• FIG. 4 illustrates the presence of the different types of pole-to-earth faults, referenced X1, X2, X3, which can occur in a mesh network provided with a power flow control device as mentioned above (represented in a way schematic in Figure 4).
• switches Q1 and Q2 In the presence of slow DC circuit breakers, switches Q1 and Q2 must have very large current sizing. However, the switches used (IGBT) in this solution do not allow strong current overloads.
• bypass / bypass switches which are reversible in current and in voltage
• the object of the invention is to propose a system which includes a power flow control device usable in a mesh network as described above for distributing the currents and suitable protection means of said device, enabling it to face external type faults identified above.
• the means of protection employed will in particular be adapted to operate on different topologies of power flow control device.
• a system intended to be used in a mesh network a mesh comprising at least three nodes each at a determined voltage
• said system comprising a power flow control device arranged to control the power flow in the mesh and which comprises a first terminal intended to be connected to a first link of the mesh, a second terminal intended to be connected to a second connection of the mesh and a third terminal intended to be connected to a connection from the network, at least one passive voltage source, switching means connected to said passive voltage source and control means configured to control said switching means to ensure a distribution of currents in said two links of the mesh, said device comprising several diodes and said switching means comprising several switches chosen from:
• a mechanical switch connected in series with a diode
• a mechanical switch connected in series with a controlled switch
• the system comprising means for detecting an electrical fault within the device and means for identifying the type of electrical fault detected,
• Said system comprising means for protecting said power flow control device, said protection means comprising:
• a bypass switch placed in parallel with each diode of the power flow control device
• a bypass switch placed in parallel with each switch of the power flow control device, except if the switch is a non-reversible controlled switch;
• a voltage limiting device connected to the terminals of each passive voltage source
• each bypass switch comprises a thyristor, two thyristors connected at the top of a spade or a group of thyristors connected in parallel and / or in series.
• each voltage limiting device comprises at least one arrester.
• the system comprises at least one voltage limiting device connected between at least two terminals of the power flow control device.
• the system comprises three terminals, a first terminal connected to said first terminal of the power flow control device, a second terminal connected to said second terminal of the power flow control device, a third terminal connected to said third terminal of the power flow control device and it comprises at least one current variation limiting device connected between one of its three terminals and the corresponding terminal of the power flow control device.
• the system comprises at least one voltage limiting device connected between two of its three terminals.
• the power flow control device comprises:
• a first voltage source connected between its first terminal and its third terminal
• a second voltage source connected between its second terminal and its third terminal
• a current source alternately connected to the first voltage source and to the second voltage source and configured to transfer energy between the first voltage source and the second voltage source
• Said switching means being configured to allow an alternating connection of said current source, in parallel with the first voltage source or in parallel with the second current source,
• control means being configured to control said switching means so as to carry out said connection of said current source alternately, in parallel with the first voltage source or in parallel with the second current source and control an energy transfer between the first voltage source and the second voltage source via said current source.
• the first voltage source comprises at least one capacitor.
• the second voltage source comprises at least one capacitor.
• the current source comprises at least one inductance.
• the switching means comprise six switches:
• a first set of two first switches connected between the first terminal and the third terminal of the device, in parallel with the first voltage source, the two switches of the first set defining between them a first connection midpoint;
• a second set of two second switches connected between the second terminal and the third terminal, in parallel with the second voltage source, the two switches of the second set defining between them a second connection midpoint;
• a third switch connected between the second terminal and the first midpoint of the first set of switches
• a fourth switch connected between the first terminal and the second midpoint of the second set of switches.
• the inductor is connected between the first midpoint and the second midpoint.
• each switch is chosen according to the sign of the following parameters:
• ⁇ ⁇ corresponds to the current flowing in the first link
• I 2 corresponds to the current flowing in the second link
• - V1 corresponds to the voltage across the terminals of the first voltage source
• each switch is chosen from:
• said power flow control device comprises a voltage source and in that the switching means comprise switches organized in three switching arms each connected in parallel to the voltage source, each switching arm comprising two switches in series, the midpoint of the first switching arm being connected to the first terminal of the device, the midpoint of the second switching arm being connected to the second terminal and the midpoint of the third switching arm being connected to the third terminal of the device.
• FIG. 1 represents a minimal mesh network with a single mesh.
• FIGS. 2 and 3 schematically represent solutions known in the state of the art of power flow control devices used in a mesh network.
• FIG. 4 schematically represents a power flow control device of the invention incorporated in a mesh network and shows the location of the pole-earth type faults, which may be present upstream and downstream of the device.
• FIGS. 5 and 6 represent known protection solutions used on power flow control devices used in a mesh network.
• FIG. 7A illustrates by a table the means employed for the protection of a power flow control device.
• the first line illustrates the protection means in general and the second line represents a particular example of embodiment of these protection means.
• FIG. 7B represents the general protection scheme applied to a power flow control device.
• FIGS. 8A, 9A and 10A represent several alternative embodiments of a power flow control device, each incorporated in a mesh network and FIGS. 8B, 9B and 10B represent these various alternative embodiments to which have been added means of protection in accordance with the principles set out in Figures 7A and 7B.
• Figure 1 1 shows an alternative embodiment of the power flow control device and Figures 1 1.1 _A, 1 1.2 A, 1 1.3_A and 1 1.4 A represent several concrete embodiments of the device of Figure 1 1.
• Figures 1 1.1 _B, 1 1 2_B, 1 1 3_B and 1 1 .4_B represent these different embodiments to which protection means have been added in accordance with the principles set out in Figures 7A and 7B.
• FIG. 12A represents the general diagram of the steps implemented during the operation of the system of the invention;
• FIG. 12B illustrates the control principles which are applied to the system according to the identified fault;
• Figure 12C shows an example of an algorithm used for fault detection for a system that includes a device conforming to two voltage sources as shown in Figure 1 1;
• FIGS. 13A to 17B illustrate different protection control sequences applied to some of the devices shown in the previous figures.
• a power flow control device of the invention (also called PFC for "Power Flow Controller”) is intended to be used in a mesh network, preferably high voltage, direct current. Depending on its configuration, it can also be used in an alternating current mesh network. This will be the case when the switching means comprise reversible power switches in current and in voltage.
• a mesh network is presented, in the simplest way, in the form of three interconnected nodes.
• Each node is advantageously connected directly or indirectly to one or more converter stations.
• the converter station A is thus connected to the first node.
• the converter station B is thus connected to the second node of the network.
• the converter station C is thus connected to the third node of the network.
• Each converter station is intended to inject power into the network or extract power from the network.
• Each converter station is intended to inject current into the network or extract current from the mesh network. These are current l a for converter station A, current l b for converter station B and current l c for converter station C.
• a voltage is imposed on each node by the station connected to the node.
• the voltage V a is applied to the first node of the network.
• the voltage V b is applied to the second node of the network.
• the voltage V c is applied to the third node of the network.
• a first link 1 1 connects the first node to the second node.
• a second link 12 connects the first node to the third node.
• a third link 13 connects the second node to the third node.
• Each link may consist of an overhead line, a cable or any other solution for transporting current.
• FIG. 4 represents a power flow control device (which can be designated hereinafter device) employed in a mesh network, inserted in a mesh of the network and forming a node between three links of the network.
• a power flow control device which can be designated hereinafter device
• such a device comprises:
• Control means 21 of said switching means configured to control the flow of power and the distribution of currents in the mesh.
• a power flow control device can be presented according to different variant embodiments described below.
• T designates a transistor
• D designates a diode
• Th designates a thyristor
• L designates an inductance
• C designates a capacitor.
• a different index (ranging from 1 to n) is added for each component of the same type present in the device, n being the total number of each component in the circuit considered.
• This solution consists in adding a passive voltage source C1 (capacitor) in series with the first link and the second link alternately, the switching means being controlled appropriately to ensure this alternating connection.
• the switching means include power switches T1, T2 of the IGBT type and are reversible in voltage thanks to the addition of a diode D1, D2 in series with each switch. This solution is described in patent application No. EP3007301 A1.
• the switching means comprise switches (T 1 to T6) of the IGBT type organized in three switching arms each connected in parallel with the voltage source, each switching arm comprising two switches in series.
• the switches are reversible in current thanks to the addition of a diode (D1 to D6) in parallel with each switch.
• the midpoint of the first switching arm (T3, T4) is connected to terminal B1 of the device, the midpoint of the second switching arm (T5, T6) is connected to terminal B2 and the midpoint of the third switching arm (T1, T2) is connected to terminal B3 of the device.
• This figure shows a "full-bridge” type power flow control device (T1 to T4) inserting a passive voltage source (capacitor C1).
• the switches thyristors Th1 to Th4 are controlled to configure the device according to the directions of the currents 11, I2 and I.
• the switches T 1 to T4 are reversible in current thanks to the addition of a diode ( D1 to D4) in parallel.
• This solution is described in patent application No. EP2975723A1 (also published under No. WO2016008927 A1).
• the device has two passive voltage sources and one current source.
• the first voltage source is connected between its first terminal (B1) and its third terminal (B3) and the second voltage source is connected between its second terminal (B2) and its third terminal (B3).
• the power source is connected alternately to the first voltage source and to the second voltage source by means of controlled switching means and makes it possible to ensure energy transfer between the first voltage source and the second voltage source.
• Control means 21 are configured to control said switching means so as to make said connection of said current source alternately, in parallel with the first voltage source or in parallel with the second voltage source and thus control the transfer of energy between the first voltage source and the second voltage source via said current source.
• the first voltage source can comprise at least a first capacitor Ci having a determined capacity.
• the second voltage source can comprise at least a second capacitor C 2 having a determined capacity.
• the current source may include an inductor L.
• the two capacitors Ci, C 2 are both connected to the third terminal B3 of the device 20 and have their other terminal connected respectively to the first terminal B1 and to the second terminal B2 of the device so as to be connected to the two links 1 1 , 12 whose currents we wish to control (h, l 2 ).
• one of the two capacitors could be connected between the terminals B1 and B2 while the other capacitor would remain connected between the terminals B1 and B3 or B2 and B3.
• the structure of the switching means is therefore chosen as a function of the network into which the device will be inserted and of the expected operating points.
• the switching means comprise six switches:
• a switch S 3 connected between the second terminal B2 of the device 20 and the first midpoint of the first set of switches
• a switch S 4 connected between the first terminal B1 of the device 20 and the second midpoint of the second set of switches;
• the inductance L is connected between the first midpoint and the second midpoint.
• switching means For each switch, switching means can then be chosen according to the sign of the following values:
• l 2 corresponds to the current flowing in the second link
• - V1 corresponds to the voltage across the terminals of the first voltage source
• V2 corresponds to the voltage across the second voltage source;
• the signs of these values define what is later called a "working case".
• some switches defined in the general architecture can be deleted (open circuit) or replaced by a permanent connection depending on the number of operating cases desired.
• switches Si to S 6 are chosen according to a particular embodiment in order to meet the need. Not exhaustively and not limiting, each switch will then be chosen according to one of the embodiments listed below:
• a short circuit i.e. a permanent connection
• a non-reversible controlled switch for example: IGBT or BJT
• a reversible current controlled switch for example: IGBT with diode in parallel or MOSFET;
• a voltage reversible controlled switch (For example: IGBT and diode in series);
• a reversible controlled switch in current and voltage (For example: two IGBTs with diode in series);
• figures 1 1.1 A, 1 1.2 A, 1 1.3_A, 1 1 .4 A represent several concrete realizations of the generic device of figure 1 1.
• the switches must be reversible in voltage.
• transistors in series with symmetrical GTO diodes or Thyristors (which support a reverse voltage) or symmetrical IGCTs.
• the principle of the invention thus consists in particular in proposing a system including a power flow control device as presented above and means of protection of this device to deal with electrical faults, in particular faults which are said to be external and which relate to faults originating from the DC network itself, such as for example a fault of pole-earth type or of pole-pole type. It should be noted that certain defects qualified as external can of course coincide with internal faults according to their location in relation to the components of the power flow control device.
• Pole-to-earth faults are indicated in Figure 4 and referenced X1, X2 and X3 for each connection to a terminal B1, B2, B3 of the device.
• the components of the device are in fact subjected to significant current and voltage stresses. In order not to force an oversizing to support these constraints, it is necessary to protect them effectively.
• the system of the invention mainly comprises:
• Protection means adapted to the topology of the power flow control device
• Fault measurement and detection means for detecting the presence of an electrical fault
• Control means configured to apply a control sequence adapted to the identified fault
• the system thus implements the following steps:
• the detection means comprise means for measuring voltage and / or current and their derivatives at the level of the device.
• the detection means may include means for measuring the voltage at the terminals of each voltage source as well as their derivatives and current measurements passing through the switches as well as their derivatives. For example, the presence of an electrical fault is detected when the voltage across a voltage source changes sign.
• the identification means are configured to locate the detected electrical fault.
• the identification carried out in the second step E2 therefore consists in determine whether the fault is of type X1, X2 or X3.
• the identification step E3 can be carried out by means of a comparison between the sign of the voltages at the terminals of the voltage sources. Knowing the sign of the voltage before the fault, the identification means can locate the fault according to the sign of the voltage after the fault.
• monitoring the derivative of a voltage also makes it possible to detect the presence of a fault. For example, if a positive voltage is measured and it decreases, it is possible to detect the presence of the fault before it has changed sign.
• the system thus comprises control means intended to control the bypass switches used in the protection means and switches or switches of the power flow control device according to the control sequence used.
• the current must not be interrupted in inductors of the power flow control device, if it has one.
• the capacitors of the power flow control device must not be short-circuited.
• Steps E30 + E31 The sequence can generally consist in closing the bypass switches at the terminals of the switches closed at the time of detection of the fault (E30) then opening the appropriate switches of the power flow control device, according to the configuration of the power flow control device (E31).
• Steps E300 + E310 The sequence can consist of opening the appropriate switches of the power flow control device (E300) and then closing the appropriate bypass switches of the protection means (E310).
• FIGS. 7 A and 7B illustrate the principle implemented to produce protection means adapted to a power flow control device used in a mesh network and comprising at least one voltage source.
• Protective means may include:
• At least voltage limiting devices (connected to the terminals of the voltage sources (surge arresters A4, A5) and possibly to the terminals of the entire power flow control device (surge arrester A6); Of a switch (Sbp) or a group of bypass switches arranged to short-circuit the switches of the device in order to protect them during current;
• inductance L1, L2, L3 Devices for limiting the variation in current (di / dt) (inductance L1, L2, L3), if necessary, for example in the case where the power flow control device itself does not have one;
• the protection means include:
• a bypass switch placed in parallel with the switch (column 4 in FIG. 7A); For each switch of the reversible current and voltage controlled switch type, a bypass switch placed in parallel with the switch (column 5 in FIG. 7 A);
• each bypass switch Sbp is chosen from a thyristor, two thyristors connected head to tail and a set of thyristors connected in parallel and / or in series. Any other switching solution could however be envisaged.
• Thyristors have the advantage of withstanding heavy current overloads for short periods of time and of being able to be closed much faster than mechanical switches.
• the switch is of the non-reversible controlled switch type, it does not necessarily require any special current protection (column 2 in FIG. 7A).
• opening it switches the current to a diode.
• the fault is detected by one of the means stated above, for example its current which exceeds the admissible value for the non-reversible controlled switch, it must be opened. Current then flows through the diode which must then be protected against current overloads.
• Each voltage limiting device A1, A2, A3, A4, .., An may comprise at least one surge arrester and / or a surge arrester in series with a spark gap or any other voltage limiting device.
• the system may include three terminals (K1, K2, K3), a first terminal (K1) connected to said first terminal (B1) of the power flow control device, a second terminal (K2) connected to said second terminal (B2 ) of the power flow control device, a third terminal (K3) connected to said third terminal (B3) of the power flow control device.
• the protection means used in the system could be the following:
• Arrester A4 connected in parallel with a first voltage source and arrester A5 connected in parallel with a second voltage source, Arrester A6 connected in parallel with the power flow control device, between terminals B1 and B2,
• inductors L1, L2 or L3 each connected between a terminal K1, K2, K3 of the system and each corresponding terminal B1, B2, B3 of the power flow control device,
• FIG. 8B thus represents the device of FIG. 8A to which the adapted protection means have been added, according to the connections defined above.
• a thyristor or set of thyristors represented in the form of a switch Sbp1, Sbp2 connected in parallel with each switch;
• a device for limiting the variation in current (inductors L1, L2, optionally L3) in series with each terminal of the device;
• FIG. 9B thus represents the device of FIG. 9A to which the adapted protection means have been added, according to the connections defined above. We thus have:
• a thyristor or a set of thyristors (Sbp1 -Sbp6) connected in parallel with each switch;
• a device for limiting the variation in current (inductors L1, L2, optionally L3) in series with each terminal of the device.
• FIG. 10B thus represents the device of FIG. 10A to which the adapted protection means have been added, according to the connections defined above. We thus have:
• a mechanical type bypass switch (Sbp1, Sbp2) connected in parallel with each switch (each formed by two thyristors Th1, Th2 and Th3, Th4);
• Figure 1 1.1 _B thus represents the device of Figure 1 1 1_A on which have been added the appropriate protection means, according to the connections defined above. We thus have:
• a surge arrester (A4, A5) connected in parallel with each voltage source, that is to say in parallel with each capacitor C1, C2;
• a surge arrester (A6) connected between the two terminals B1 and B2 of the power flow control device;
• a device for limiting the variation in current in series with each terminal of the device.
• Figure 1 1.2_B thus represents the device of Figure 1 1.2_A to which have been added the appropriate protection means, according to the connections defined above. We thus have:
• a surge arrester (A4, A5) connected in parallel with each voltage source, that is to say in parallel with each capacitor C1, C2;
• a surge arrester (A6) connected between the two terminals B1 and B2 of the power flow control device;
• a device for limiting the variation in current in series with each terminal of the device.
• Figure 1 1.3_B thus represents the device of Figure 1 1.3_A on which have been added the appropriate protection means, according to the connections defined above. We thus have:
• a thyristor or a set of thyristors (Sbp1, Sbp2) connected in parallel with each switch of the reversible voltage-controlled switch type (IGBT + diode in series), oriented in the same direction as the diode;
• a surge arrester (A4, A5) connected in parallel with each voltage source, that is to say in parallel with each capacitor;
• a surge arrester (A6) connected between the two terminals B1 and B2 of the power flow control device;
• Figure 1 1 .4_B thus represents the device of Figure 1 1 .4_A on which have been added the suitable protection means, according to the connections defined above.
• a thyristor or a set of thyristors (Sbp1, Sbp2) connected in parallel with each diode D1, D2;
• a surge arrester (A4, A5) connected in parallel with each voltage source, that is to say in parallel with each capacitor;
• a surge arrester (A6) connected between the two terminals B1 and B2 of the power flow control device;
• a device for limiting the variation in current in series with each terminal of the device.
• Figure 12C shows an identification algorithm, which can be used to identify a fault in a network controlled by a device with two voltage sources such as that of Figure 1 1. This algorithm can be executed during the second step E2 mentioned above in connection with FIGS. 12A and 12B.
• the algorithm is based on the measurements of the voltage across the capacitor C1 and the voltage across the capacitor C2.
• V1_m If the voltage V1_m is greater than or equal to V1 lim and becomes positive (it was initially negative), the fault is then of type X1 or X3.
• the fault is of type X1.
• the fault is of type X3.
• a step of comparing the voltage difference DV_m across the terminals of the power flow control device with respect to a threshold value DVmax In parallel, a step of comparing the voltage difference DV_m across the terminals of the power flow control device with respect to a threshold value DVmax.
• the control means can have several separate control sequences, according to the different types of fault.
• FIGS. 13A to 17B different control sequences are illustrated.
• the gray lines show the different actions taken as well as the direction of the current in the power flow control device used. Of course, these sequences are to be considered in a nonlimiting manner and other operating variants can of course be implemented.
• Step 1 Detection / identification of the fault according to the principles mentioned above.
• Step 3 Open the Tx transistor (and leave the other transistor open).
• Figures 14A and 14B
• Step 1 Detection / identification of the fault according to the principles mentioned above.
• Step 2 Open transistor T2 and transistor T5 which were closed during normal operation.
• Step 3 Close the bypass switches Sbp1, Sbp3 and Sbp6.
• Figures 15A and 15B
• Step 1 Detection / identification of the fault according to the principles mentioned above.
• Step 2 Open the transistor T 1.
• Step 3 Close the switch Sbp1 (optional, because in this case, the current in the inductor decreases).
• Step 1 Detection / identification of the fault according to the principles mentioned above.
• Step 2 Open the transistors T 1 and T2.
• Step 3 Close the switches Sbp1 and Sbp2.
• Figures 17A and 17B are identical to Figures 17A and 17B:
• Step 1 Detection / identification of the fault according to the principles mentioned above.
• Step 2 To cancel the current, close the transistor T2 if the voltage V2 is positive or close the transistor T1 if the voltage V1 is positive.
• the proposed solution perfectly reduces physical constraints. It is simple to produce and requires standard voltage and current protection elements such as surge arresters and / or spark gaps and / or inductors and thyristors.
• the proposed solution is "independent" of the network into which the device is inserted because it provides intrinsic protection independent of the overall network protection system. This is of major interest, especially when the device is installed after installing the network.
• the proposed solution (arrangement of the physical elements and the associated protection algorithm) is generic and applicable to the entire family of power flow control devices provided with voltage sources and / or current sources, some of which have been described above and shown in Figures 8 to 11.
• the proposed solution allows the detection and localization of faults and in some application cases, in particular with two voltage sources, it offers a method of locating faults in the global network. This information can be communicated to the overall network protection system.

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• 2018
  • 2018-06-25 FR FR1855652A patent/FR3083019B1/fr not_active Expired - Fee Related
• 2019
  • 2019-06-24 EP EP19731772.0A patent/EP3799671B1/de active Active
  • 2019-06-24 WO PCT/EP2019/066718 patent/WO2020002266A1/fr unknown

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